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Transcription does what?
Makes it usable � into mRNA and the body can read this
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Translation
Makes into functional proteins
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Genes�
hereditary factors responsible for traits
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Alleles�
different forms of genes
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Rules of Inheritance
- Alleles of the same gene separate during gamete formation
- Alleles of different genes are inherited independently
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What is a Gene?
- Genes are made of nucleic acids
- Nucleic acids are made of building blocks called nucleotides
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Nucleotides have three components, what are they?
- Sugar molecule (ribose or deoxyribose)
- Phosphate molecule
- Nitrogen-containing molecule (adenine, guanine, cytosine, thymine, uracil)
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DNA is
deoxyribonucleic acid
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Nucleotides are linked in a chain through
sugar-phosphate interactions
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DNA molecules are made of two chains of
nucleotides wound around each other in a helix
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Base pairs hold the chains together
- A pairs with T
- G pairs with C
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The Human Genome Project:
Sequencing DNA and Cataloguing Genes
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Genome�
the collection of DNA molecules that is characteristic of an organism
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Genomics is the
- analysis of DNA sequences that make up a genome
- Genomics involves DNA sequencing technology, robotics, and computer science
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The Human Genome Project determined the sequence of nucleotides in the DNA of the human genome
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A Milestone in Genetics:
- fX174, the First DNA Genome Sequenced
- fX174 is a virus that has single-stranded DNA as its genetic material.
- Frederick Sanger sequenced the genome of fX174 in 1977
- Gregor Mendel postulated the existence of particular factors�now called genes�to explain how traits are inherited.
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Alleles, the alternate forms of genes, account for
heritable differences among individuals.
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James Watson and Francis Crick elucidated the structure of DNA, a macromolecule composed of two complementary chains of nucleotides.
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DNA is the hereditary material of all life forms except some types of viruses, in which what is the hereditary material?
RNA is the hereditary material.
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The Human Genome Project determined the
sequence of nucleotides in the DNA of the human genome.
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Sequencing the DNA of a genome provides the data to identify and catalogue all the genes of an organism.
DNA as the Genetic Material
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Information flows from
DNA to RNA to protein.
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In all cellular organisms, the genetic material is
DNA.
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The genetic material
- Must be able to replicate
- Must contain information
- Must be able to change
- DNA Replication is based on the complementary nature of the
- two strands of duplex DNA molecules.
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When the two parental strands are separated, the separated strands can serve as
template for the synthesis of new strands.
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New strands are assembled by incorporating nucleotides according to
base-pairing rules.
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At the end of replication, each template strand is paired with a newly synthesized
partner strand.
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DNA replication is catalyzed by
enzymes.
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Gene Expression
- During transcription, an RNA molecule is synthesized from a DNA template.This messenger RNA (mRNA) molecules contains the information needed to synthesize a polypeptide.
- During translation, the triplet codons in the RNA specify the incorporation of particular what?
- amino acids into a polypeptide chain.
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Proteome�
the collection of all the different proteins in an organism.
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Humans have between ____ and ___ genes in the genome and hundreds of thousands of proteins in the proteome.
20,000 and 25,000
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Proteomics�
the study of all the proteins in cells.
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The Central Dogma of Molecular Biology
The flow of information is DNA � RNA� protein.
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Some viruses can use RNA as a template for the synthesis of DNA in
reverse transcription.
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Many genes do not encode polypeptides; their end-products are
RNA molecules.
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Mutation:
Changing Genetic Information
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When DNA replicates, each strand of a duplex molecule serves as the template for the synthesis of a
complementary strand.
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When genetic information is expressed, one strand of a gene�s DNA duplex is used as a template for the synthesis of a
complementary strand of DNA.
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For most genes, RNA synthesis (transcription) generates a molecule (the RNA transcript) that becomes
a messenger RNA (mRNA).
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Coded information in an mRNA is translated into a sequence of amino acids in a
polypeptide.
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The genetic variability created by mutation is the basis for
biological evolution.
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Variation in the DNA sequence makes it possible for species to
evolve over time.
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Organisms with similar DNA sequences are descended from a
common ancestor.
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A phylogenetic tree, or phylogeny, represents the
historical relationships among organisms.
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Evolution depends on the occurrence, transmission, and spread of
mutant genes in groups of organisms.
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DNA sequence data provide a way of studying the
historical process of evolution.
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Geneticists approach their science from different points of view�
from that of a gene, a DNA molecule, or a population of organisms.
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Classical Genetics
- Based on analysis of the outcomes of crosses between different strains of organisms.
- Can be coordinated with studies of the structure and behavior of chromosomes.
- Encompasses transmission genetics and studies of the nature of the genetic material
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Molecular Genetics
- Studies the replication, expression, and mutation of genes at the molecular level.
- Rooted in the study of DNA sequences and the manipulation of DNA molecules.
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Population Genetics
- Individuals within a population may carry different alleles of genes.
- Population genetics is based on analyzing allele frequencies in a population and determining whether these frequencies changes over time.
- Population genetics includes evolution and the inheritance of complex traits.
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In classical genetic analysis, genes are studied by following the
inheritance of traits in crosses between different strains of an organism.
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In molecular genetic analysis, genes are studied by
isolating, sequencing, and manipulating DNA and by examining the products of gene expression.
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In population genetic analysis, genes are studied by
assessing the variability among individuals in a group of organisms.
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Genetics in Agriculture:
- Selective Breeding
- Genetically Modified Organisms
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Genetically Modified Organisms (GMOs) are have been altered by
the introduction of foreign genes.
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Genetics in Medicine
- Inborn Errors of Metabolism are metabolic abnormalities caused to mutant alleles.
- Genetic Counselors advise people about inheritance of genetic diseases.
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Molecular genetics
- new ways to detect mutant alleles.
- new ways to treat diseases.
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Economic impact�
biotechnology industry, pharmaceutical industry.
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Legal impact�
paternity testing, forensics, identification
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Discoveries in genetics are changing procedures and practices in agriculture and medicine.
Advances in genetics are raising ethical, legal, political, social, and philosophical questions.
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